1. Technical Field
The present invention relates generally to an ultrasonic diagnostic apparatus and ultrasonic image processing method.
2. Description of the Related Art
An ultrasonic diagnostic apparatus is one of the important diagnostic apparatuses that have been variously applied. In particular, ultrasonic diagnostic apparatuses have been widely used in the medical field thanks to the characteristics of being non-invasive and non-destructive to a target. Recent high-performance ultrasonic systems are being used to generate a two-dimensional or three-dimensional image of the inside of a target.
Generally, an ultrasonic diagnostic apparatus is configured to receive the echoes which are obtained when a part of the ultrasonic waves transmitted from an ultrasonic probe are reflected from a structural variation point (variation plane) of the internal tissue of the target, and to generate a tomogram of the target on the basis of the echoes.
In this way, an ultrasonic image is generated by collecting reflected waves (echoes) which are returned from the internal tissue of the target while ultrasonic waves emitted from the ultrasonic probe are propagated to the internal tissue of the target.
In order to diagnose the internal tissue of a human body, conventional ultrasonic diagnostic apparatuses are operated to generate an ultrasonic image, as described above. In this case, a beam is focused on the assumption that all the regions of the internal tissue of a human body have the same sound velocity (for example, about 1540 m/s). However, the tissue of a human body has a unique sound velocity depending on the type of media.
Therefore, a difference may occur between the actual sound velocity and the assumed sound velocity for each tissue of a human body, and may influence reflected waves which are returned from each tissue of the human body after the ultrasonic beam has been reflected from the tissue.
Accordingly, as the difference between the actual sound velocity and the assumed sound velocity of each internal tissue of the human body increases, a difference between the reflected waves may also increase. As a result, a problem arises in that the beam reflected from the internal tissue of the human body is defocused, so that an image is distorted, thus deteriorating resolution and tissue contrast.